Samples of natural gas taken before it was burned for cooking in homes in the Boston area contained 296 chemical compounds, Including 21 that are toxic to humans, researchers led by the Harvard T.H. Chan School of Public Health report.
The toxic compounds included hexane, toluene, heptane, cyclohexane and benzene, a known carcinogen. The researchers also found the so-called odorant level added to natural gas as a safety precaution varied and could be undetectable by human noses, suggesting that federal guidelines need to be adjusted to address this inconsistency, they wrote.
The results were published Tuesday in the journal Environmental Science and Technology and added to a growing body of research into the potential health and climate risks of natural gas, even as reliance on this fuel has increased.
The study comes as some cities and states move to ban gas-fired appliances in new construction in favor of electric appliances. In January, researchers at Stanford reported that methane leaks from residential gas stoves were far greater than previously thought and had a 20-year climate impact comparable to carbon dioxide emissions of half a million cars. They also wrote that combustion pollutants released inside homes from burning gas could trigger respiratory diseases.
About half of all United States’ homes use natural gas for cooking and heating every day. With every click of the stove and turn of the thermostat, consumers are harnessing the energy of natural gas piped hundreds, even thousands, of miles from its original source.
Natural gas is mostly methane, a greenhouse gas with more than 80 times the warming power of carbon dioxide over a 20-year period. But, when burned, methane produces less carbon dioxide than burning coal, leading to its promotion as a “bridge fuel” in the energy transition.
Of the 234 samples collected from 69 homes, 95 percent had low levels of benzene, which is linked to anemia, decreased immune function and cancer. The presence of benzene and other toxic compounds raises the question of the health impact of natural gas in homes but is not a cause for panic, said Drew Michanowicz, a visiting scientist with the Center for Climate, Health and Global Environment and lead author on the new study.
The study only looked at the presence of hazards like benzene in the natural gas itself before it was burned, not whether home users are exposed to these compounds in the ambient air.
Michanowicz said the findings should prompt scientists and energy experts to consider whether natural gas is harming the public in ways health researchers now understand. “What are the costs of this system?” he asked.
Rob Jackson, professor of earth system science at Stanford University and co-author of the January study that found higher than anticipated methane leaks from gas stoves, said the new Harvard research would help give scientists and policymakers better data on overall…
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